1. Field of the Invention
This invention relates generally to orbital welders, and more particularly to a novel alignment system facilitating easy tube alignment within orbital welders.
2. Description of the Background Art
Orbital welders are widely used in the construction of fluid handling systems, for example semiconductor processing equipment. Known orbital welders join metal tubes in an end-to-end fashion by forming a flat, circular weld around the circumference of the tubes' opposing ends. One problem encountered by conventional orbital welders is that the ends of the tubes which are to be joined must be precisely aligned prior to performing the welding operation.
When aligning tubes in an orbital welder, there are several conditions which must be met before the welding operation can begin. First, the seam where the weld will be formed must be aligned with the weld tip to ensure proper bead coverage at the tube interface. Another condition which must be monitored is the alignment of the open ends of the tubes with one another when abutted in the orbital welder. This condition ensures that the mating ends of the tubes are both laterally (axially) aligned and planar (flat) perpendicular to the running directions of the tubes. The final condition required when aligning tubes in an orbital welder is checking the ovality of the mating ends of the tubes to ensure that the mating ends of the tubes are substantially circular.
As a result of these requirements, aligning the mating ends of two tubes within prior art orbital welders has been notoriously time-consuming and/or resulted in a relatively high number of unacceptable welds. For example, it is common for a skilled operator to require a minimum of 5 minutes to align a pair of tubes using such orbital welders. The alignment of tubes is time-consuming because the operator must align the mating ends of the tubes merely by eye, while keeping the above alignment conditions in check. Additionally, the area within the orbital welder where alignment must occur is generally enclosed and not well-illuminated, also hindering the alignment process. Finally, the operator must also prevent external influences, such as the tube clamping process and external vibrations, from upsetting the alignment of the tubes.
FIG. 1 is a top plan view of a typical orbital welder 100, which includes an insulating body 102, tube clamps 104 and 106, a rotor 108, a weld tip 110, and a rotation and voltage controller 112. Clamps 104 and 106 hold tubes 114 and 116, respectively, in position for welding, and are maintained at a common voltage (e.g., ground) and in electrical contact with tubes 114 and 116. Rotor 108 is disposed within body 102 so as to be rotatable about an axis 118 passing through the center of the open ends of tubes 114 and 116. Body 102 provides electrical insulation between rotor 108 and clamps 104 and 106. Rotation and voltage controller 112 functions to rotate rotor 108 within body 102, and to apply a voltage, via rotor 108, to attached weld tip 110.
FIG. 2 shows a cross-sectional view of orbital welder 100, taken along line A—A of FIG. 1. As controller 112 rotates rotor 108 about axis 118 and applies a high voltage to weld tip 110, an arc weld 202 is formed between the open ends of tubes 114 and 116. Because clamps 104 and 106 are held at the common voltage, they must be displaced a safe distance from weld tip 110, so as not to generate an arc there between. The distance between clamps 104 and 106 and the open ends of tubes 114 and 116 makes alignment of the open ends of tubes 114 and 116 more difficult. Moreover, as discussed above, the interior chambers of known orbital welders are dark, and, therefore, visual confirmation of proper alignment is difficult.
What is needed is an orbital welder that facilitates efficient alignment of the tube pieces that are to be welded. What is also needed is an orbital welder that facilitates easy confirmation of proper alignment.